If storms are worse now, why did they need a sea wall 150 years ago?

From Virginia Tech something that makes you wonder about past storm intensity and the need to protect shorelines from storms coming from the sea. With all the hype surrounding “Superstorm Sandy”, it is interesting to see that 150 years ago, simple engineering made the storm less intense in this one area.

Virginia Tech researchers say relic seawall came in handy for New Jersey town

A forgotten, 1,260-meter seawall buried beneath the beach helped Bay Head weather Sandy’s record storm surges and large waves over multiple high tides, according to a team of engineers and geoscientists led by Jennifer L. Irish, an authority on storm surge, tsunami inundation, and erosion at Virginia Tech. Credit: Jennifer Irish/Virginia Tech

Picture two residential beach communities on the New Jersey shore: Bay Head and Mantoloking, which sit side-by-side in Ocean County on a narrow barrier island that separates the Atlantic Ocean and Barnegat Bay.

Before Hurricane Sandy landed on Oct. 29, 2012, a motorist traveling north on Ocean Avenue would seamlessly travel through Mantoloking into Bay Head, noticing few changes in residential development, dunes, beaches, and shoreline.

The difference was hidden under the sand.

A forgotten, 1,260-meter seawall buried beneath the beach helped Bay Head weather Sandy’s record storm surges and large waves over multiple high tides, according to a team of engineers and geoscientists led by Jennifer L. Irish, an associate professor of civil and environmental engineering in the College of Engineering at Virginia Tech and an authority on storm surge, tsunami inundation, and erosion.

The stone structure dates back to 1882. Its reappearance surprised many area residents, underscoring the difficulties transient communities have in planning for future threats at their shores, the researchers said.

“It’s amazing that a seawall built nearly 150 years ago, naturally hidden under beach sands, and forgotten, should have a major positive effect under the conditions in which it was originally designed to perform,” said H. Richard Lane, program director in the National Science Foundation‘s (NSF) Division of Earth Sciences, which funded the research. “This finding should have major implications for planning, as sea level rises and storms increase in intensity in response to global warming.”

The discovery, now online in the journal Coastal Engineering and slated for the October print edition, illustrates the need for multi-levels of beach protection in oceanfront communities, the researchers said.

“Once we got there, we immediately saw the seawall,” Irish said. “The beach and dunes did their job to a certain point, then, the seawall took over, providing significant dampening of the waves. It was the difference between houses that were flooded in Bay Head and houses that were reduced to piles of rubble in Mantoloking.”

With recovery efforts under way and storms still circulating through the area, Irish and Robert Weiss, an assistant professor of geosciences in the College of Science at Virginia Tech, with Patrick Lynett, an associate professor of civil and environmental engineering at the University of Southern California, documented high water marks, damage, overwash, and breaches of the barrier island.

All oceanfront homes in the two boroughs were damaged, ranging from ground-floor flooding to complete destruction. As measured by water lines on the interior of homes, flooding was similar in both boroughs. The difference was the extent of the storm’s impact.

In Mantoloking, the entire dune almost vanished. Water washed over the barrier spit and opened three breaches of 165 meters, 59 meters, and 35 meters, where the land was swept away. In Bay Head, only the portion of the dune located seaward of the seawall was eroded and the section of dune behind the seawall received only minor local scouring.

Later, using Google Earth to evaluate aerial images taken two years before and immediately after Hurricane Sandy, the research team evaluated houses, labeling a structure with a different roofline as damaged, one that no longer sits on its foundation as destroyed, and the remaining houses as flooded.

The researchers classified 88 percent of the oceanfront homes in Bay Head as flooded, with just one oceanfront home destroyed. In Mantoloking, more than half of the oceanfront homes were classified as damaged or destroyed.

Despite the immense magnitude and duration of the storm, a relatively small coastal obstacle reduced potential wave loads by a factor of two and was the difference between widespread destruction and minor structural impacts, the researchers said.

“We have a great deal of compassion for the people who have had to endure the devastation of Hurricane Sandy in Bay Head and Mantoloking,” Irish said. “It will have little solace, but we are left with a clear, unintentional example of the need for multiple levels of defense that include hard structures and beach nourishment to protect coastal communities.”

###

This research was supported by the National Science Foundation via grant EAR-1312813.

I often say to disbelieving friends that newer is not only not better, but usually it is worse. Here’s an example that goes further back than even I had expected. I’m reminded of the modern academic study which intended to embellish and correct an 1870’s study of how some birds’ feathers are blue — since no pigmentation is that color. The modern study in the end not only completely validated the old study, but marvelled at its rigor and exactitude which was way beyond the experience of the modern researchers. They were smart in those days. It’s been all downhill throughout the past 100 years, most unfortunately.

150 years ago it was around 0.7 degrees cooler than today and the false gods of climate computer models were not even a figment of anyone’s imagination.
There was real science back then, not the type of science where the results are known before the research gets funded, as is all too often the case today, especially in ‘climate science’.
Someone decided a wall was needed to protect the coastline against the effects of bad weather – that’s just common sense. Today, in order to get funded, you would need to demonstrate that you wanted to protect the coastline against the effects of man made climate change.
The ecoloons have somehow made far too many of us believe that all bad weather is the obvious consequence of man made global warming/climate change/whatever.
As always, scary = funding.

Mmm!
There are groynes along the beach at Bay Head, but none at Matoloking. Don’t normally disagree with engineers, but the groynes means sand accumulated on Bay Head beaches and was lost at Matoloking, assuming north to south along shore drift. If south to north along shore drift then just sand accumulation at Bay Head, but still better protected by those groynes.

See! I told you guys to trust engineers to solve our future problems. I admit it will be based upon the ability of scientists to present unflawed science based on empirical observation, & “some” puter modelling up to a point. The real trouble is when we start designing defences based upon flawed data provided by said scientists! I suppose we could invoke our own standard Precautionary Principle, called in the UK “Murphy’s Law”, in which if it can go wrong it will go wrong!!!! 😉

Barrier islands do what barrier islands have always done, as Willis pithily reminded us the other day. Any one building anything on a barrier island had better work out where King Cnut went wrong. The fact that the wall had been covered with sand for the remembered past is a give away that these ephemeral strips of shifting storm toss should not be relied to be there in the morning.

Peter Miller said:
July 17, 2013 at 1:35 am
Today, in order to get funded, you would need to demonstrate that you wanted to protect the coastline against the effects of man made climate change.
————————————————-
But after you got the funding, some enviroschmucks would get an activist judge to issue an injunction against building the seawall because it might threaten some “endangered” sand flea.

So we use Google Earth now to evaluate flood damage? Really? So a house that didn’t move was “flooded”, one that did move was “damaged”, and one that moved a lot was “destroyed”. That’s some fine-grained research there.

The ones that run are VC, the ones that don’t run are well disciplined VC…

“This finding should have major implications for planning, as sea level rises and storms increase in intensity in response to global warming.”
And there it is. The usual, obligatory, anti-scientific Warmist dogma. And they have the nerve to call themselves “scientists”.

So the old wall reduced the wave energy and prevented the destruction of houses, but was overtopped as it did not prevent the flooding. Perhaps the rise in sea level since 1882 has made it too low.
1882 was one year when Tyndall gave Royal Institution lectures on heat, visible and invisible and water and air. Athough the discovery of the absorbative properties of CO2, the basis for the ‘greenhouse effect’, was actually measured a couple of decades earlier.

@Nick Luke
King Cnut was right, not wrong. The story is often garbled, but the King wasn’t demonstrating that he thought he could hold back the sea, he was demonstrating the limits of power. He knew he could not hold back the sea. Only Obama has that kind of power.

Abstract – 2012
Persistent non-solar forcing of Holocene storm dynamics in coastal sedimentary archives
…..Here we present a reappraisal of high-energy estuarine and coastal sedimentary records from the southern coast of the English Channel, and report evidence for five distinct periods during the Holocene when storminess was enhanced during the past 6,500 years. We find that high storm activity occurred periodically with a frequency of about 1,500 years, closely related to cold and windy periods diagnosed earlier…..http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1619.html
_______________________________________
Among other things, the three researchers report that (1) “the content of marine-source ssNa aerosols in the GISP2 ice core record, a proxy for storminess over the adjacent ocean through the advection of salt spray [ss], is high during the LIA with a marked transition from reduced levels during the MCA [hereafter MWP] (Meeker and Mayewski, 2002; Dawson et al., 2007),” (2) “the onset of the LIA in NW Europe is notably marked by coastal dune development across western European coastlines linked to very strong winds during storms (Clarke and Rendell, 2009; Hansom and Hall, 2009)” and often inundating local settlements and therefore with supporting archival evidence (Lamb, 1995; Bailey et al., 2001),” (3) “a number of studies of Aeolian sand deposition records from western Denmark exist that have recorded a period of destabilization of coastal sand dunes and sand migration during the LIA and have ascribed it to a combination of increased storminess and sea-level fluctuationshttp://nipccreport.com/articles/2012/sep/11sep2012a4.html

Philip Bradley says:
July 17, 2013 at 1:39 am
> There are groynes along the beach at Bay Head, but none at Matoloking….
I’m no groin (US spelling) expert, but on my last visit to Long Beach Island decades ago groins had been installed and I climbed around them curious about the accumulation and depletion.
In this case, I don’t think the groins had much effect as the storm surge overtopped the groins and any accumulated sand. The photo at the top shows really clearly how the seawall absorbed the wave energy below the scouring level.
It also brings home how weak Sandy was there. A decent hurricane or nor’easter would have had no trouble ripping out that seawall.

The only way this could possibly be explained is that there must’ve been a United Nations back then that we don’t know about. Just like today, that would account for the peace and tranquility they experienced back then. More to the point, that UN must’ve had an Intergovernmental Panel on Climate Change. And that IPCC, no doubt, was able to peer 130 years into the future (it’s an old science really, Nostradamus was able to do it) and recognize that human contribution of CO2 into the atmosphere was going to cause sea level rise and Hurricane Sandy in 2012. So the IPCC ordered that infrastructure change for our own good. Sure, CO2 spewing universal electricity, automobiles, and jet aircraft were not even a glimmer in the eye back in 1882, but the UN could foretell these things 100 years into the future just like the Mayans knew what was going to happen in 2012 (ok, scrap that idea). Anyway, this is the only reason I can think of as the reason for the presence of that sea wall. And the only reason it didn’t extend beyond Mantoloking must’ve been because there was a sequester that blocked further funding. Now, I’m from Chicago, and if anybody questions my explanation I have one question, “Are you sure you’ve paid your taxes?”

Jimbo
Storms are worse when the psyentists say they are worse.
Once the present GW scare has run its course and the temps are on their way down again, then storms will be worse when it’s colder.
At the moment the grant money is on storms will be worse when it’s warmer.
Do keep up!

Some Studies of the Little Ice Age of Recent Centuries and its Great Storms
Hubert H. Lamb
[Climatic Changes on a Yearly to Millennial Basis1984, pp 309-329]
And so the series gives us our most reliable estimate of the magnitude of the temperature depression in England and neighbouring countries. In northern Scotland, southern Norway and Iceland there are indications of a significantly greater depression of the prevailing temperatures……………The enhanced thermal gradient between latitudes about 50° and 60–65°N in this part of the world is thought to have provided a basis for the development of some greater wind storms in these latitudes than have occurred in most of the last 100 years, though there are signs that in about the last decade or two storminess has been increasing again………….http://link.springer.com/chapter/10.1007/978-94-015-7692-5_34
Millennial-scale storminess variability in the northeastern United States during the Holocene epoch
Before European settlement of the area at ,250 yr BP,
when deforestation and livestock grazing accelerated rates of hill-
slope erosion (which overprints our record3), sediment delivery
appears to have been increasing toward another peak. This most
recent period of increased delivery began at about 600yr BP,
coincident with the beginning of the Little Ice Age (LIA)14; the
earliest such period peaked during the Younger Dryas climate
interval1ftp://texmex.mit.edu/pub/emanuel/Paleo/Uvermont_storms.pdf‎

NZ Willy says:
July 17, 2013 at 12:20 am
The modern study in the end not only completely validated the old study, but marvelled at its rigor and exactitude which was way beyond the experience of the modern researchers.
============
you find the same thing in ocean charts. the British Admiralty charts from the time of Cook, Bligh, Vancouver and Flinders show magnificent detail. it is strange that with much of the world’s economy based on shipping, nowhere on the modern charts is there a datum correction for global sea level rise. especially since just a 1 foot difference in ocean levels can mean the difference in millions of dollars in shipping costs.
yet the modern charts were almost without exception drawn from the older charts. the vast majority of the ocean depths have not been resurveyed since the age of exploration. It is simply too expensive as compared to the cost of press gangs and rum. so why is there no datum correction on ocean charts for sea level rise? Every modern chart has a WGS84 datum correction to align the world to Transit/GPS. Why not for sea level rise?

Richard Muller:
“Most of your skepticism is still valid. When something extraordinary happens in weather, such as the accidental occurrence of Hurricane Sandy hitting New Jersey and New York City just at the peak of tides — many people attribute the event to “climate change.” That’s not a scientific conclusion, and it is almost certainly wrong. Hurricanes are not increasing due to human causes (actually, they have been decreasing over the past 250 years).”http://judithcurry.com/2012/12/13/week-in-review-121512/

“This finding should have major implications for planning, as sea level rises and storms increase in intensity in response to global warming.”
With this one line, Mr. Lane almost destroyed the credibility of this report. The idiots from NSF should just present the research and keep their biased mouths shut.

What I want to know from the experts is this: will global warming lead to the same effect as below? Just askin. :-p

………..From a meteorological point of view, this troublesome development in the late medieval time was the result of global cooling. When the planet cools, the cooling is especially pronounced near the poles and smaller near the equator. Along with planetary cooling, this therefore produces an enhanched thermal contrast between equatorial regions and the poles. In the northern hemisphere, this thermal contrast tend to develop especially in latitudes between about 50 and 65oN, in the zone of westerlies. This strengthened thermal gradient is the basis for development of more cyclonic storms over oceans in this zone, leading to increasing flood frequency and damage for adjoining coasts and land areas……..Climate4you.com

Galveston had a seawall,
Just to keep the water down,
But the high tide from the ocean,
Blew the water all over town,
— “Wasn’t that a mighty storm” – old blues tune
Must have been caused by climate change! /sarc

“It’s amazing that a seawall built nearly 150 years ago, naturally hidden under beach sands, and forgotten, should have a major positive effect under the conditions in which it was originally designed to perform,” said H. Richard Lane, program director in the National Science Foundation‘s (NSF) Division of Earth Sciences, which funded the research. “This finding should have major implications for planning, as sea level rises and storms increase in intensity in response to global warming.”
This is pretty well gibberish. It is a surprise that the wall did what it was meant to do? That makes no sense. The conclusion is equally dim. If and when “sea level rises” or “storms increase,” the discovery that sea walls work has a “major” implication for planners? Gosh.

izen says:
July 17, 2013 at 5:41 am1882 was one year when Tyndall gave Royal Institution lectures on heat, visible and invisible and water and air. Athough the discovery of the absorbative properties of CO2, the basis for the ‘greenhouse effect’, was actually measured a couple of decades earlier.
Unlike todays carbon clowns of climatism, John Tyndall was a true scientist. If he were alive today, he’d be profoundly shocked and saddened by what has been done to science by the Warmist Brotherhood. Indeed, he would almost certainly be in the “denier” camp.

The sea wall resembles ship ballast. The whole wall was probably free and just one family recycling ship ballast into a wall to protect private property. So the wise use of garbage is the answer to some of our biggest “problems”. Just think what we could do with all the sea cans that China sends us.

Yeah, Duster, that phrase, “It’s amazing … ,” was the ENTIRE article in a nutshell. (head shake).
That ANYONE (“scientist” or not) would publicly assert such a thing is what is amazing.
I mean, MAN ALIVE, it’s like that Dumb [Communist — a group I don’t MIND offending] Joke, where the man saws and saws and saws all day with his new saw, but, only managing to cut WAY less than the guaranteed cords per day, walks back into the hardware store to get his money back and, upon the store owner firing up the chain saw, gasps, “What’s that noise?! Or, to quote my scientist brother, ‘Amazing.’ ”
********************
“breakwater” — “bulkhead” — “rip-rap” — “sea wall” — NEVER heard it called a “groyne.” Never. And, unless an Australian comes to town, we never will, either (at least, not in this neck of the U.S.A. woods) LOL.

From Wikipedia,
A groyne (groin in the United States) is a rigid hydraulic structure built from an ocean shore (in coastal engineering) or from a bank (in rivers) that interrupts water flow and limits the movement of sediment. In the ocean, groynes create beaches, or avoid having them washed away by longshore drift. In a river, groynes prevent erosion and ice-jamming, which in turn aids navigation. Ocean groynes run generally perpendicular to the shore, extending from the upper foreshore or beach into the water.
A groyne creates and maintains a wide area of beach or sediment on its updrift side, and reduces erosion on the other. It is a physical barrier to stop sediment transport in the direction of longshore drift (also called longshore transport). This causes a build-up, which is often accompanied by accelerated erosion of the downdrift beach, which receives little or no sand from longshore drift (this is known as terminal groyne syndrome, as it occurs after the terminal groyne in a group of groynes).

We vacation almost every year at the Delaware shore. A couple of summers ago, I bought a book on the local history. The inlets up and down that coast had been violently relocated by hurricanes and tropical storms roughly every 50 years. That stopped when massive construction projects carved and cemented “permanent” inlets. The beach house we rent is on a section of beach that didn’t exist 100 years ago. A major storm relocated the river that flowed into the sound and silt then depositied to fill in the sound as the river found another outlet.
I wonder what climate scientists would have predicted for that beach back then?
Oh, fortunately, “climate scientists” didn’t exit back then, and the scientists that did study such issues weren’t so arrogant as to have tried to predict 100 years out. Of course, they had no NSF to encourage them in their false arrogance.

That seawall was most likely built by the NY&LB Railroad. Bay Head was and still is the southern terminus for that line (now NJ Transit operated); although at one time a spur ran down through Mantoloking to Seaside, it was not worth protecting as it only handled summer excursion traffic.
There is a similar wall at Sea Bright, further north near Sandy Hook. The railroad there is long gone, but the seawall has kept Sea Bright from being swept away on an almost decadal basis.
As for Sandy’s storm strength, winds were at or just below hurricane strength as it came ashore from near Atlantic City to New York harbor. Due to the large radius of the storm, winds, waves and tides had a long “fetch”. If I remember correctly, it also occurred within a day of a full moon (increased tide height). Winds at Belmar were a good steady (not gusts) 40mph from the east at 4 PM when the storm center was still about 200 miles offshore and 300 miles from Belmar.
Yes, them old guys did know a thing or two, especially about protecting their capital investment.

@ Phillip Bradley — Never. You won’t catch ANY red-blooded American in these parts (along the west coast of Washington State) using that term in that context. No matter HOW MANY TIMES you post about it on WUWT. #[:)]
Thanks so much for sharing.

Shhhh! You are not supposed to mention historical things like this, the sheeple are supposed to forget common sense and accumulated knowledge from generation to generation. How else can the bureaucrats keep them properly herded? You’re gonna spoil a perfectly good meme here, that the Jersey shore is an innocent coast subject to unprecedented torture from human-corrupted seas.
You’ve heard of corporate welfare, welcome to coastal welfare. It is a key component of the AGW hoax. The leftists with exploit every possible angle of the weather to run up the red ink of public spending to collapse the entire system.
Here’s a Google map of where Hurricane ( aka Tropical Storm ) Sandy came ashore above Atlantic City and below Seaside Heights …http://goo.gl/maps/q80X8
… click it to satellite view and scroll in to zoom and you will see a coastline that is woefully vulnerable to everything from storms to plain old rain. For extra bonus points have a look at the almost indestructible piers in Atlantic City versus the dilapidated shoddy junk up in Seaside where government handouts will be spent.
I wonder if Governor Krispy Kreme and President DingleBarry ever wondered how that coast became a narrow strip of barrier Islands in the first place? The locals choose to reside on the tattered remains of thousands of years of tidal weathering, radical sea-level rise and fierce winds, yet they expect the rest of the country to bail them out, literally. It’s like our very own little Maldives. How awesome.

“CharlieL says: July 17, 2013 at 5:36 pm
That seawall was most likely built by the NY&LB Railroad. Bay Head was and still is the southern terminus for that line (now NJ Transit operated); although at one time a spur ran down through Mantoloking to Seaside, it was not worth protecting as it only handled summer excursion traffic.
There is a similar wall at Sea Bright, further north near Sandy Hook. The railroad there is long gone, but the seawall has kept Sea Bright from being swept away on an almost decadal basis…”

Possibly; whatever the reason, modifications to the New Jersey Beach was big news in the late nineteenth and early twentieth century. People, especially in New York City and Philadelphia spent part or all of their summers down at the Jersey shore. A month at the shore was not uncommon.
New Jersey has a long coastline of beautiful yellow sand. Not as fine a sand as the sugar sand found along the Florida panhandle, but fine enough that the sand flowed readily, drained and dried easily and is pleasant to walk or lounge on. Rocks are almost always brought in by man. Like building those groynes (groins groynes whatever, I learned groyne). That bit is just for you Janice. ;> hearing people use the word groyne is similar to people requesting a John Hartford song and getting “Hey babe, you want to boogie?” (Don’t blame me if you go listen, you deserve it then.)
The railroad mentioned by Charlie and others ran regular trips bringing beachgoers to and from the beach. Any changes to ‘their’ beach was followed closely by beachgoers planning their next trip.
Whatever the reason; newspapers in Philadelphia, Atlantic City and New York probably kept up with the modifications. Atlantic City or the archives in Ocean County likely have copies of the original permits.
What is not likely, is that the wall was built as any type of true sea wall to protect residences. Whether as railroad grade, a strong possibility or just as beach erosion protection the wall is not high enough to be a true sea wall. The wall may have served to protect Bay Head from significant damage from Sandy, but I doubt that it would serve as such for a major hurricane.
For a side note; my family once had a great time collecting clams at Sandy Hook when I was young. There was a hurricane passing close off shore and the surf was dredging up lots of clams and flinging them on the beach. My Father took one look at the surf’s actions and went to ask the park ranger, came back and handed out buckets to us young clam collectors. Yes, we were the only crackpots on the beach and since the surf was way too rough for fun, well clam bakes are always wonderful.

bw said, on July 17, 2013 at 7:57 AM:
“Sustained wind speeds measured at the surface define storm strength. The recorded sustained surface wind speeds of Sandy were well below hurricane threshold.”
But what about all the hurricanes that are classified while they are over areas lacking surface instruments? That is why the National Hurricane Center often uses extrapolations from various non-surface means. And, especially in “Nor’Easter country”, worse still inland, the wind is very unsteady and sustained qualifying winds get spotty – despite lots of very impressive gusts.
Nevertheless, Sandy did achieve a “hurricane-qualifying” land-based wind measurement, somewhere on Long Island near NYC, at altitude above the surface higher than the official 10 meters but unlikely by much. While its worst sustained winds were over water, and in an unusual region of the hurricane – probably due to Sandy being *at least almost* more a Nor’Easter than a hurricane an hour or 2 before landfall.
Consider the wind speeds of the should-still-be-famous late October 1991 storm – that sucked in a hurricane, and degraded into a hurricane. But while it was biggest and worst, as a Nor’Easter, it was spectacularly bad – despite low presence of “hurricane-qualifying-sustained” winds.

While not disputing any of the history of the area, especially as cited by the locals, it is worth remembering that building isolated seawalls is not all it is cracked up to be. In fact, it can worsen erosion by deflecting the wave energy and the water to places either side of the seawall (which might be why the adjoining communities in this example fared much worse). Depending on the circumstances, it can also accelerate the loss of sand directly in front of the seawall, meaning that over time the wall itself is subjected to more and more battering and erosion from underneath, and can then collapse dramatically in a big storm leaving the land behind it more exposed than it would have been if the coastline had developed naturally over a period.
Coastlines are tricky things for humans to manage, especially in places subject to erosion, and the ‘solutions’ that seem intuitively correct can be counter-productive

“breakwater” — “bulkhead” — “rip-rap” — “sea wall” — NEVER heard it called a “groyne.” Never. And, unless an Australian comes to town, we never will, either (at least, not in this neck of the U.S.A. woods) LOL.

I don’t know what the etymology of groyne or groin is for any definition, but IIRC the various definitions of the terms you mention are:breakwater
A structure parallel to the coast (and with legs connecting to the coast) designed to block waves from the coast. Typically used to create calm water ports.bulkhead
I’ve only heard this in ship design, not coastal construction. Hmm, maybe as the wall along a channel.rip-rap
Like a seawall, but generally just large rocks or concrete pieces dumped along a shoreline to stop erosion.sea wall
Like rip-rap, but done with design and care, and it often concrete poured in place.
On the other hand, a groin is perpendicular to the coast and is designed to impede the littoral transport of sand and other sediments along the coast. They risk causing some erosion next to the groin where the sand supply is blocked.
I don’t have much experience along the west coast except in the rocky areas, so I don’t recall seeing groins there. They’re common along the east coast.

If someone tried to build a little seawall like that now, you’d have homeowners demanding something big enough to not just protect their properties from destruction but flooding as well.
Once the politicians had buckled under to that idea, then the environmentalists would come in and start banging their kitchenware, and nothing would get built for a quarter-century if ever.

Well, yes good engineering was and is a solution to protect against natural disasters. Question is if they are left to build that and the fundings are available…
Does anybody know, would the Katrina New Orleans’ disaster have been avoided if the initial design would have been followed? “Hurricane Betsy in 1965 alerted a new generation to the threat of major hurricane hits. As radar showed the storm heading for the city, a mandatory evacuation of Eastern New Orleans was declared. The Mississippi River-Gulf Outlet Canal channeled storm surge into the metro area.[citation needed] A levee failure was responsible for major flooding in Lower 9th Ward.
The heavy flooding caused by Hurricane Betsy brought concerns regarding flooding from hurricanes to the forefront. Betsy resulted in major redesign of levee system. By authorizing the United States Army Corps of Engineers to design and construct the flood protection, Congress essentially overrode responsibility for the local flood protection by the local levee boards. The Flood Control Act of 1965 directed the Corps of Engineers to design and construct the flood protection for the maximum anticipated hurricane for the area. (This project was still under construction when the city was hit by Katrina 40 years later.)
The Corps of Engineers also designed a Lake Pontchartrain Hurricane Barrier to shield the city with flood gates like those that protect the Netherlands from the North Sea. Congress provided funding and construction began in 1971, but work stopped in 1977 when a federal judge ruled, in a suit brought by the environmental group Save Our Wetlands, that the Corps’ environmental impact statement was deficient. In 1985, after nearly a decade of court battles, the Corps scrapped the plan, and decided on reinforcing the city’s levee system instead.”https://en.wikipedia.org/wiki/Hurricane_preparedness_for_New_Orleans

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